In reply to:
yamaha's ratings are always bloated
I don't think Yamaha's ratings are bloated. Rather they merely adhere to the FTC spec which doesn't require all channels of a 5-chan amp to output 100% simultaneously. Yamaha doesn't claim to do this.
Some other manufacturers CAN do all channels driven simultaneously drive at 100%. If you think that's important, then buy those.
How important is it? In your situation your powered subwoofer off loads most of the power requirement. By far most amp power is required for bass.
Freed from this, 0.1 watts per channel will be loud (on efficient Axiom speakers), and 1 watt per channel will be very loud.
Of that small amount, most wattage goes to the front channels, not the surrounds. HT or music multi-channel mixes typically don't put much sustained output on the surrounds. The real world likelihood of any material demanding 100% simultaneously on all channels is low.
Even if you de-rate your amps power by 50%, it's still way sufficient. From a power standpoint, you are fine.
But if anyone wants to buy HK, Denon, or other amps capable of rated power when all channels fully driven, that's fine, too. It's comforting to know you've got the power on all channels simultaneously.
